Dispensers are known where such viscous materials are dispensed by means of a piston that forms the base of a cylindrical container and that in use is advanced so that it exerts pressure upon fluid stored in a cylinder and so discharges the fluid through an aperture or nozzle. However such dispensers suffer the disadvantage that they continue to dispense fluid for a short time after the user ceases to activate the device. This results in wastage of the material being dispensed; a particular problem when the material is an expensive cosmetic or medicament.